IF THE SAN JOSE SYMPHONY gave guest conductor Mario Bernardi their best in last Friday's Mozart/Bruckner program, then they need a vacation. At this point in the season, opening nights should not have to put up with opening-night jitters. Jitters is probably not the right explanation, but something certainly kept the strings from developing any real intensity until well through the one-hour Symphony no. 9 by Bruckner.

It almost seemed as if the tremendous sonorities of brass and winds finally persuaded them to dig up some enthusiasm, some energy, some pride in their work. In the closing pages of the final movement, concertmaster Robin Mayforth and her fellow violinists suddenly produced a forceful fortissimo. The effect was as startling as it was, by that late hour, unexpected.

This is not to say that the strings didn't generate some impressive sonorities of their own. The cellos, for example, produced some moments of grand warmth and tone. But moments do not a complete performance make. And after a while, blaming the acoustic failings of the hall starts to sound like an excuse for not figuring out a compensatory strategy. Sooner or later, the room--even the conductor--aside, these musicians owe their subscribers better.

Canadian conductor Bernardi comes with impressive credentials. A short man with a shock of white hair, he used as much body English as stick technique. He also knew his scores, leaving a pocket edition of the Bruckner alone on his desk while cueing players and shaping the performance from beginning to end.

Bruckner remains a hard sell in America, even though his voice is unique and curiously influential where the German language prevails. He links Schubert to Mahler, in spite of Wagner and Brahms, who disdained him as a bumpkin, a throwback. Still, he demonstrates a glorious (if somewhat incoherent) grasp of sonata forms, a start-and-stop sequencing of events that give his architecture a preclassical exuberance, a miniaturism despite spectacular edifices.

This only adds to the Bruckner puzzle. It takes a conductor of equal vision, like Sergiu Celibidache, to put Bruckner across the footlights, to clarify his place in the 20th- (and 21st-) century concert repertoire. Moreover, mystique is only emphasized by the paucity of authoritative Brucknerites, a rarefied fraternity with scarcely more members than Bruno Walter, Otto Klemperer and Wilhelm Furtwängler. (Celibidache seems to have felt the same when he wrote, "I can't help thinking it's a gift of the gods to have lived when Bruckner was discovered.")

To trace the development of Bruckner is as easy--and perhaps as daunting--as experiencing the symphonies one after another. An immense arch appears, a Gothic cathedral of sound and glory, an architecture that seems too fragile to support its great weight. And, look Ma, no flying buttresses.

Ah, but this is where the strings are so crucial, where their presence must pop and rattle like a skeleton of steel. Instead of taking charge of this function, the San Jose strings left the sprawling work structurally unsupported and (to underscore the analogy) unsound. In this, his last piece, Bruckner calls for a palette knife to complement his paint brush, cutting edges sharply, framing brighter reflecting surfaces with deeper shadows and bolder relief. String players are taught by their teachers to use their bows like artists use their brushes. Bernardi needed to convince them to also use their bows like knives.

Most memorable, the wind band, enlarged by the addition of four Wagner tubas, came through with those requisite torrents of awesome sound. Time and again, in the outer movements, tremendous washes of sonority made the room rumble. In the scherzo, demonically hammered volleys brought into hard focus an image of Vesuvian doom.

At these moments, the previously heard Prague Symphony of Mozart faded from memory. Another three-movement Austrian opus--this one presumably complete--set a relaxed tone for the evening that, like the succeeding Bruckner, lacked string intensity. It is difficult to imagine how a work of this stature would have attracted its long and illustrious list of fans without more energy. Gemütlich is always desirable in Viennese music, but not more than paprika.